Dual dado machine

ABSTRACT

For use with a work member such as a wood strip there is provided a dual dado machine with a main frame having at the front a magazine for a stack of several of the strips. The bottom strip is fed from the magazine simultaneously to occupy a couple of work sites on the main frame. The strip is accurately positioned endwise and is clamped on the main frame by hold down devices. A pair of dado cutters are movable simultaneously from the back of the main frame and in selectable and preferably converging paths through the work sites to make dado cuts through the top of the held strip. The cutters are then returnable to the back of the main frame. The cut strip is released by the hold down devices and is ejected from the machine. The operating sequences are preferably automatically controlled.

United States Patent 1191 Sandberg [4 1 Oct. 1, 1974 1 DUAL DADO MACHINE Ernest J. Sandberg, Red Bluff, Calif.

[73] Assignee: Commander lndustries, 1nc., Red

Bluff, Calif.

[22] Filed: July 27, 1973 [21] v Appl. No.: 383,171

[75] Inventor:

[52] US. Cl. 144/133 R, 83/82, 83/417, 83/112, 144/136 R, 144/245 E, 144/253 F [51] Int. Cl B27c 5/06, B27f 1/08 [58] Field of Search 83/417, 471.2, 471.3, 474, 83/488, 82, 112; 144/3 R, 3 A, 3 B, 3 C, 136 R, 133 R, 242 R, 242 K, 245 R, 245 E, 253

Primary Examiner Andrew R. Juhasz Assistant ExaminerW. D. Bray I Attorney, Agent, or Firm-Lothrop & West 5 7] ABSTRACT For use with a work member such as a wood strip there is provided a dual dado machine with a main frame having at the front a magazine for a stack of several of the strips. The bottom strip is fed from the magazine simultaneously to occupy a couple of work sites on the main frame. The strip is accurately positioned endwise and is clamped on the main frame by hold down devices. A pair of dado cutters are movable simultaneously from the back of the main frame and in selectable and preferably converging paths through the work sites to make dado cuts through the top of the held strip. The cutters are then returnable to the back of the main frame. The cut strip is released by the hold down devices and is ejected from the machine. The operating sequences are preferably automatically controlled.

15 Claims, 7 Drawing Figures PAIENTEB 3,838,723.

sum ear 5 EAIENTEBBBT 11w 3.838.723 sneer aur s PATENTEU BB1 J :574

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PATENIEnum nan HEE 50F s DUAL DADO MACHINE In the manufacture of various items from stock such as wood strip. there are often repetitive operations on successive pieces which can very economically be performed by machinery that is automatic or semiautomatic. It is important, however, that such ma'chinery can readily be adapted to a wide variety of changes in the articles being worked on so that a variety of products can be turned out. Also in certain fields, such as the building industry, much of the work that formerly was done on the site by carpenters or comparable workmen is now more economically done in a central plant which furnishes the completed or nearly completed material for final use at the site.

One of the items which lends itself to factory production rather than individual fabrication on the site is the frame of a door. Such frames are usually standardized within relatively narrow limits and are made in quite similar fashion, although there are some variatitins in sizes and configurations. One of the parts of a door frame which lends itself to special construction is the vertical side rail of the frame. Such a frame usually has two side rails each with a dado or groove near one end for the frame head and another dado or groove, usually somewhat larger, and customarily inclined, to receive the door sill.

It is therefore an object of the invention to provide a dual dado machine effective to operate on the side member of a door frame simultaneously to cut the head dado and the sill dado in proper location and with proper dimensions and inclinations.

Another object of the invention is to provide a dual dado machine that can be used to operate on a single work member or can be operated automatically on a succession of work members.

' Another object of the invention is to provide a dual dado machine that simultaneously makes a plurality of dado cuts in a work member.

A further object of the invention is to provide a dual dado machine that can readily be set up adjusted or arranged to afford a wide range of working configurations.

Another object of the invention is to provide a dual dado machine that can maintain a high degree of accuracy in its finished work.

A further object of the invention is to provide a dual dado machine which is relatively easy to construct, operate and maintain.

A further object of the invention is in general to provide a greatly improved dual dado machine.

Other objects, together with the foregoing, are attained in the embodiment of the invention described in the accompanying description and illustrated in the accompanying drawings, in which:

FIG. I is a diagram in isometric perspective showing the relationship of some of the major elements of the disclosure; 1

FIG. 2 is a plan of a machine constructed pursuant to the invention, a work member being shown therein by broken lines and certain parts being broken away to reduce the complexity of the showing;

FIG. 3 is a cross-section to an enlarged scale through cated by the line 3-3 of FIG. 2;

FIG. 4 is a cross-section showing a detail of the machine, the plane of section being indicated by the line 4-4 of FIG. 2;

FIG. 5 is a cross-section of another detail of the machine, the plane of section being indicated by the line 5-5 of FIG. 2;

FIG. 6 is a cross-section of the device, the plane of section being indicated by the line 66 of FIG. 3; and

FIG. 7 is a detail shown in cross-section, the plane of which is indicated by the line 77 of FIG. 6.

While the dual dado machine pursuant to the invention can be constructed in various different ways and particularly can be adapted for widely variant uses, it is explained herein in connection with its use commercially as a device for providing dados in the side rail of exterior door frame. Such side rail in one instance is received for further work by the dual dado machine from previous operations and is a work piece 6, usually of wood, having a generally rectangular form with a top surface 7, a bottom surface 8, a side surface 9, end surfaces 11 and 12 and composite side surfaces 13 and 14 spaced by a relatively small top surface 16. The length of the work member 6 is more or less accurately cut previously at a predetermined value although for a nominal length of, say, 6 feet 9 inches, theactual, received length may vary about a half inch or so. However, the other bounding surfaces of the work piece are fairly accurately cut and the material is usually received in reasonably straight, unwarpedcondition.

Also shown in FIG. 1, is a finished work piece 6' which is substantially identical with the initially received work piece 6 except that its length is accurately cut and it is also provided with a frame head dado cut 17, the bottom of which is substantially coplanar with the top surface 16 and the sides of which are usually normal to the top surface 7 and extend for the full width of the top surface 7. The head dado cut 17 is a predetermined distance from the finished end 12'. Near the other end 11 there is also provided a sill dado cut 18, the bottom of which is substantially coplanar with the top surface 16 and the side edges of which are parallel to each other but are not normal to the side edges of the work member; i.e., the dado cut 18 converges toward the dado cut 17. Furthermore, the dado cut 18 usually is somewhat wider than the dado cut 17.

In order to start with a rough work member 6 and furnish a finished work member 6, there is, pursuant to the invention, provided a dual dado machine, as largely shown in FIGS. 2 and 3. The machine is erected on a floor 21 and includes a main frame, generally designated 22, and made up of numerous shapes and angles preferably of metal and appropriately secured together to afford a generally rectangular, table-like support. The frame 22, as particularly shown in FIG. 2, is considerably longer than it is high or wide and hence is termed elongated and abitrarily has a front portion 23 and a rear portion 24. Included in and supported from the other parts of the frame are stationary extensions 26 and 27 of somewhat box-like nature projecting from the front portion 23 and arranged generally parallel to each other.

Mounted on transversely extending portions of the main frame 22 are double acting cylinder mechanisms 28 and 29 which can be actuated by any suitable pressure substance, such as compressed air, or hydraulic fluid. Preferably the actuation is by air. As an example, the cylinder mechanism 29 (FIG. 3) is at one end pro vided with an anchor 31 to hold it stationary on the frame and is also provided with connections 32 and 33 to a suitable compressed air mechanism, not shown in detail. Much of the control piping, valving and other instrumentalities are omitted from the drawings to avoid complexity but the connections are generally standard and well known. The cylinder mechanism 29 is likewise held in frame blocks 34, one of which also passes a piston rod 36 from the cylinder. A cross head 37 is secured to the piston rod 36 and likewise is connected to plunger rods 38 and 39. These extend parallel to the cylinder and run toward the front of the frame where they are fixed to a magazine plunger frame 41.

The cylinder mechaism 28 is a virtual duplicate of the cylinder mechanism 29 and is similarly connected to a duplicate magazine plunger frame 42 near the other end of the main frame. The machine is arranged in mirror symmetry about a vertical, transverse, central plane so that the description of one part of the structure in detail applies to a comparable structure in symmetrical relationship therewith.

Included in each of the magazine frames 41 and 42 is a feeding plate 43, supported on reinforcing bars 44. The feeding plate is a generally fiat plate of uniform thickness except at one, cantilevered end whereat the feeding plate 43 has a cut in the upper surface to leave a shoulder and a relatively thin finger 46 projecting therefrom.

Designed to cooperate with the plates 43 are adjacent magazine holders each incorporating a pairof side bars 47 and 48 as well as an end bar 49. These are inclined upwardly and outwardly at their upper ends and at their lower ends are secured by appropriate fasteners 51 to the main frame 22. At least one of the sides bars, such as 47, is preferably secured by the fasteners 51 in any one of several adjusted positions. The side members 47 and 48 are spaced to lie rather closely to the sides of a stack 52 made up of a number of work pieces 6 of whatever selected width is being operated on at a particular time. Usually the end members 49 are not made adjustable since there is only a small variation in length of materials handled and other mechanism, later described, is utilized for accurate positioning. In the position of the parts shown in FIG. 3, the lowermost work member 6 by gravity rests upon the fingers 46 of the two feeding plates 43 when the plates are in an extreme position (right-hand) as seen in FIG. 3.

For the operation of this portion of the mechanism, pressure fluid is admitted to the connection 33 of both of the hydraulic members 28 and 29 so that the piston rods 36 are expelled therefrom. This translates the pairs of rods 38 and 39 toward the left in FIG. 3 so that the rods as supported by the cross head 37 and as guided in the blocks 34 correspondingly translate the magazine plunger frames 41 and 42 toward the left.

In order to make sure that both magazine plunger frames 41 and 42 operatesynchronously despite possible pressure variations in the two hydraulic mechanisms 28 and 29, there is provided on the main frame 22 a cross shaft 56 journalled for oscillation and at its opposite ends carrying a pair of levers 57, each of which has a slot 58 in the outer end thereof interengaging a pin 59 on an adjacent one of the rods 39. Thus, the piston rods 36 and the magazine frames 41 and 42,

although separately impelled. must necessarily travel in synchronism.

As the frames 41 and 42 move toward the left in FIG. 3, the shoulders formed between the fingers 46 and the main plates 43 are in engagement with the side edge 14 of the lowermost one of the work pieces 6 in the stack 52. The lower work piece is, therefore, displaced simultaneously near both ends toward the left in FIG. 3 but the immediately superposed work pieces, as soon as the lowermost one is clear of the stack, then drop down part way and the lower one rests upon the subjacent plates 43, being temporarily supported thereby.

As the work piece 6 is thus displaced toward the left in FIG. 3, it travels through an intervening space and then rides up on the cammed leading end of a pair of support shoes 61 and 62 having their upper surfaces substantially at the same level as the bottom of the transported work piece 6, any slight discrepancy in elevation being taken care of by a cam surface 60. Adjustably mounted upper shoes 65 having cammed entrances hold the moving work piece below a set elevation.

In the final portion of the leftward movement of the magazine frames 41 and 42, the lowermost work piece 6 is shifted onto the shoes 61 and 62 until the work piece comes substantially into abutment with stops 63 adjustably positioned by fasteners 64 which hold them onto the main frame. Also during the final movement of the magazine frames, the work piece comes into contact with and moves a control lever 67 effective to reverse the power fluid connection to the cylinder mechanisms 28 and 29. They no longer tend to move the carriage frames 41 and 42 toward the left in FIG. 3 but rather, with reverse connections, such members are reversed toward the right in FIG. 3 and eventually return to initial position.

Should the work piece not be left behind on the shoes 61 and 62 as desired, the work piece is nevertheless restrained by a depending pair of pawls 68 that permit advancement of work pieces into the machine but block retrograde movement thereof. The work piece is, therefore, delivered from the stack 52 to the shoes 61 and 62 and is ready for subsequent operations.

Since the length of the work member is not necessarily exact but since it is desired to have an appropriate datum point for the rest of the operations, there is provided, particularly as shown in FIG. 6, a gauge angle 71 at the left end of the main machine frame 22. This is appropriately mounted with adjustable securing devices 72 and has an inclined lead-in 73. A work piece being advanced into the machine toward the shoes encounters the incline 73, if necessary, but in any event comes to rest about opposite to and either against or slightly spaced from the gauge angle 71.

In a comparable position but at the right end of the main frame 22, there is provided a similar gauge plate 74 having an inclined lead-in 76. In this instance, the gauge plate 74 is not fixed on the frame directly but rather has a pair of posts 77 guided in a frame 78 slidably guided by upright fastenings 79 on the main frame. The frame 78 has a connection 81 to the piston rod of a cylinder mechanism 83 fastened on the main frame but by a bracket 84. With this mechanism there is afforded a wide entrance for the work piece which generally comes to rest approximately in position so far as its length is concerned and more or less distant from the gauge angle 71.

When the cylinder mechanisms 28 and 29 are reversed, or slightly before that time, the cylinder 83 is energized with compressed air and is effective through the connections 81 to translate the frame 78, to he left in FIG. 6, through springs 85 to move the datum plate 74 tightly against the end of the work member. The urgency of the mechanism is such that the work member is moved lengthwise until its far end 11 firmly abuts the datum angle 71, thus establishing the left end of the work member as the datum end from which all dimensions of length are measured. Should there be overtravel in the mechanism, the springs 85 yield to take it up and ascertain that no damage is done despite the use of a relatively strong positioning force. By this means the fed work member is accurately located laterally against the stops 63 and as well longitudinally against the datum angle 71.

There is then imposed a further restraint upon the work member so positioned. At appropriate points on the main frame 22, particularly as shown in FIG. 3, there are mounted hold down devices 86 and 87. These are virtually duplicates of each other, not only side-byside but at the opposite ends of the machine. They are generally controlled simultaneously from the supply of compressed air. When operated there is a simultaneous expulsion of plungers 88 and 89 therefrom near both ends of the work member and in abutment with the top 7 and with the panel 16. When pressure is exerted by the hold downs 86 and 87, the force is sufficiently great as to hold the ends of the work piece substantially immobile.

In addition, there is sometimes provided on a central member 91 of the main frame (FIG/2 and FIG. 5) a bracket 92 supporting a single hold down device 93 having a plunger 94. The hold down 93 is actuated simultaneously with the hold down 86 and 87 and comes into contact with the top surface 7 near the central portion of the work member which is so held against the front part of the central member 91. The frame member 91 extends forwardly and has a beveled surface 96 corresponding generally to the cam surface 60. The work member is initially easily positioned. In this fashion the work member is not only located at the back and at one end but is also clamped firmly in the center and adjacent both ends. Even if warped the work member is held substantially flat. When the hold downs are effective additional mechanism is brought into play.

A pair of dado cutting devices is disposed in the rear portion 24 of the machine. As illustrated especially in FIGS. 2 and 3, from the main frame 22 near the rear corners thereof there arise supports 101 and 102. Each of these is substantially like the other so that the description of one applies as well to the other. The supports are arranged substantially symmetrically and with their axes vertical. Each support, such as 102, is tubular and contains a slidable and rotatable plunger 103 therein. The plunger can be clamped in position in the upright by appropriate, firm clamping means, not shown. The slidable and rotatable plunger 103 at its upper end carries a dado saw frame 104 which is movable in an are about the axis of the mounting 102 and is movable vertically but always remains parallel to itself.

The frame 104 includes a pair of rectilinear ways 106 and 107. Guides 108 included in a pivot frame 109 for an electric motor 111 slide between the ways 106 and 107. On the shaft 112 of the motor is mounted a group of dado cutters 113, as particularly shown in FIGS. 4 and 1. The dado cutters are set for the desired width of the dado cut. The height at which the various frames are clamped is such that the dado cutters 113 at their lowermost extent coincide with the plane of the surface 16.

In the usual positioning of these mechanisms, the frame 104, at the right in FIG. 2, is usually set so that the ways 106 and 107 are normal to the longitudinal dimension of the work piece. The left-hand saw frame, as shown in FIG. 2, is usually set at somewhatof an angle so that the ways 106 and 107 thereof converge toward the front of the machine with respect to the right-hand member. This is illustrated in FIG. 1.

As part of this arrangement, each of the frames 104, as especially shown in FIG 4, carries a hydraulic mechanism 116 anchored on theframe and having a piston rod 117 projecting in a forward direction therefrom and connected to an adaptor bracket 118 that is secured to the saw frame 109. The connections to the hydraulic mechanism 116 are such that when pressure fluid is supplied thereto when the parts are in the position of FIG. 4, the piston rod 117 is expelled and is movedtoward the left in FIG.'4. In turn, the bracket 118 moves the frame guides 108 through the ways 106 and 107 in the predetermined path.

While this action occurs the motor 111 is energized. The dado cutters 113 are advanced from the full line position shown in FIG. 4 tothe broken line position therein through a sufficient distance to encounter and cut the held work piece on the shoes 61. As the frame 109 advances and cuts through the work piece it also advances a reverse rod 121 (FIG. 3) which ultimately comes into abutment with and actuates a control lever 122 at the extreme forward position of the motor frame. This reverses the pressure supply to the cylinder mechanism 116 and sends the piston rod 1 17 back into the cylinder, thus retracting the traveling saw frame to its initial position. Thereupon another control 123 is contacted to stop the cylinder mechanism 116.

The effect of the traverse of a dado cutter is to provide the dado cut such as 17. Simultaneously, the other dado mechanism on the support 101 is operating similarly and produces the dado cut 18. The twocylinders 1 16, both the right-hand and the left-hand ones, are simultaneously energized so that the two dado cutters operate in substantial synchronism. If desired, a cut-off saw 124 (shown dotted in FIG. 6) can be included with the cutters 113 to make a finish end cut of the piece 6, but usually this is done as a subsequent operation.

When the dado cutter frames 109 are retracted and back in their full line positions, as shown in FIG. 4 or in FIG. 3, the cutting operation has been completed. Thereupon, preferably as actuated by the controller 123, there is a release of the pressure fluid from the hold downs 86 and 87 as well as from the hold down 93, thus removing the vertical restraint from the work member. At the same time, if it has not occurred previously, pressure fluid is released from the datum cylinder 83 so thatthe work member is free at its ends.

At this time an ejector mechanism 126 (FIGS. 2,5 and 6) is also conveniently supplied with actuating fluid. This mechanism includes a cylinder 127 secured to the frame bracket 91 and having a piston rod 128 extending therefrom. The rod 128 carries an ejector shoe 129 normally in abutment with or close to the rear face 9 of the work member. When the cylinder 127 is supplied with air under pressure. the piston rod 128 is projected and the shoe 129 pushes on the central portion of the work member to advance the entire member toward the front of the machine. The work member travels over the inclines 60 and 96 and falls by gravity onto the upper run 131 of a conveyor belt 132 (FIGS. 1 and 2) mounted on the main frame and disposed in the space intervening between the magazine portion and the hold down portion of the device.

The effect of the ejector shoe 129 is to clear the machine of the just completed work member to the extent of getting the finished work member low enough to be out of the way of the magazine. The upper run of the belt 132 which generally travels in the direction of the arrow 133 in FIG. 2 carries the work piece out of the machine. The cycle has thus been completed and the machine is available to recycle and to repeat the operation with the now lowermost work member in the magazine.

The new cycle can easily be initiated by an operator depressing a foot pedal 134 (FIG. 3) which reenergizes the cylinder mechanisms 28 and 29. If desired, this can also be accomplished automatically by a switch mechanism 136 effective when the ejector mechanism 126 is restored to its retracted position and when one or more sensing switches 137, mounted on part of the magazine structure, are activated. That is, the next or lowermost work member can start to be removed from the magazine when the ejector 126 is home after its just-finished ejection, provided there is in fact a subsequent work member available in the lowermost position of the magazine and resting upon the switches 137 (see FIGS. 2, 6 and 7). Under the automatic mode of operation a machine operator is not necessary. It is then ony necessary to keep the magazine loaded with work members, each work member going through the cycle, as described, and being provided with a pair of dado cuts, as described, and being ejected from the machine automatically on the belt 132.

There are many variations possible with this particular setup. For example, in the event it is desired to make only one dado cut in a work member, it is simple to deenergize one of the dado cutters and even to swing it out of the way, if preferred. Furthermore, additional dado cutters can be employed in the same fashion as the two dado cutters described. Also, work members of different lengths, widths and thicknesses can be accommodated by appropriately setting or adjusting the machine. The controls can be arranged for manual operation but preferably so that each element, when it has finished its cycle, automatically energizes the next succeeding element. Alternatively, the device can be provided with a central program control to operate each of the various control instrumentalities from a central point and in accordance with a timed program.

The operation of the device is initiated by actuation of the foot pedal 134 by an operator or, in the automatic mode, by the presence of at least one work member 6 supported on the switches 137 located adjacent the opposite end bars 49 (see FIGS. 6 and 7) In other words, the weight of even a single work member on the switches 137 is sufficient to actuate the switches 137. If no work member is present in the magazine, the switches 137 will not be actuated, thereby providing a self-terminating feature in the automatic mode.

If the two switches 137 are actuated. however, by the presence of a work member, and if the ejector mechanism 126 has returned to base, or home, position so as to actuate the switch mechanism 136 (see FIG. 2), the concurrent actuation of the three switches will initiate the new cycle of operation.

At the start of the cycle, compressed air is valved by operation of the foot pedal 134 or the actuation of the switches 136 and 137 into the connections 33 in the double acting cylinder mechanisms 28 and 29, thereby ejecting the plunger rods 38 and 39 in a rearward direction so that the two feeding plates 43 displace the lowermost work member 6 in the magazine toward the left, as it appears in FIGS. 1 and 3, onto the support shoes 61 and 62 and into abutment with the control lever 67 which reverses the power fluid connection to the cylinder mechanisms 28 and 29, thereby returning the feeding plates 43 to the base position shown in full line in FIG. 3.

At the time the cylinder mechanisms 28 and 29 are reversed by actuation of the control lever 67, the cylinder 83 is energized with compressed air, so as to abut the work member against the datum angle 71 (see FIG. 6); and substantially instantaneously thereafter the pairs of hold down devices 86 and 87 located at both work sites go into operation, together with the central, single hold down device 93 (see FIG. 2), thereby securely clamping the work piece adjacent both ends and in the center.

At this juncture, the two dado cutters 113 are advanced toward the front by actuation of the cylinder mechanism 116 and engage and cut the work member 6, as indicated most clearly in FIG. 1. As the reverse rod 121 mounted on the dado frame 109 (see FIG. 3) engages the control lever 122, the pressure connections to the cylinder mechanism 116 are reversed and the two dado frames are retracted toward base position. Upon reaching base position, the control lever 123 is contacted, thereby stopping the cylinder mechanism 116 and completing the cutting operation.

Thereupon, preferably as actuated by the control lever 123, pressure is released from the two end pairs of hold downs 86 and 87 and the central hold down 93. Concurrently, if not before, pressure fluid is released from the datum cylinder 83.

The work member 6 is thereby freed of all restraints and, through operation of the ejector mechanism 126 (see FIGS. 2, 5 and 6), is urged forwardly, passing over the inclines and 96 and falling by gravity onto the conveyor belt 132 for transfer to another location.

The cycle is thus completed and the machine is ready to recycle with a new work member in lowermost position in the magazine. As previously indicated, the new cycle is initiated either by actuation of the foot pedal 134, by an operator, or by return of the ejector mechanism 126 to base position thereby actuating the switch 136 which cooperates with the sensing switches 137 to commence the new cycle in the automatic mode.

What is claimed is:

l. A dual dado machine for use with an elongated work member having top, bottom and end surfaces comprising an elongated main frame extending through two work sites, a magazine on said frame for supporting a stack of said work members, means on said main frame for transferring a work member from said stack in said magazine to said work sites simultaneously, means on said main frame for holding said work memher in said work sites. a pair of dado cutters, means for simultaneously moving both of said dado cutters on said main frame transversely and each into and out of a respective one of said work sites, and means on said main frame for ejecting said work member from said main frame.

2. A machine as in claim 1 including means responsive to the presence of a work member in said work sites for controlling operation of said transferring means.

3. A machine as in claim 1 including means responsive to the presence of a work member in said work sites for controlling operation of said moving means.

4. A machine as in claim 3 in which said controlling means is effective to move said dado cutters simultaneously into said work sites and then simultaneously out of said work sites.

5. A machine as in claim 1 in which said moving means includes means for guiding-said dado cutters to move in predetermined paths.

6. A machine as in claim 5 in which said paths are converging.

7. A machine as in claim 5 in which said paths are parallel.

8. A machine as in claim 1 including means for urging said work member longitudinally in said work sites.

9. A machine as in claim 8 including a datum block and in which said urging means is effective on an end of said work member in a direction toward said datum block.

10. A dual dado machine for use with an elongated work member having top, bottom and end surfaces comprising an elongated main frame having a front portion and a rear portion, a pair of supports upstanding from said main frame in said rear portion thereof and spaced apart longitudinally of said main frame, dado cutter guides on said supports and extending transversely of said main frame, dado cutters movable along said guides, means on said main frame for simultaneously so moving said dado cutters, means on said main frame for holding a work member in a predetermined position for substantially simultaneous engagement by said moving dado cutters, and means for movably connecting at least one of said dado cutter guides to the respective one of said supports.

11. A machine as in claim 10 including means for establishing a predetermined travel of said dado cutters on said guides.

12. A machine as in claim 10 including means disposed on said front portion of said main frame for feeding a work member into said predetermined position on said main frame.

13. A machine as in claim 10 including means on said main frame for ejecting a work member from said predetermined position into said front portion of said mainframe.

l4.'A machine as in claim 13 including a conveyor on said main frame in said front portion thereof for receiving a work member from said ejecting means.

15. A machine as in claim 12 including a magazine for a stack of work members mounted on said main frame in said front portion thereof and for supplying said work members to said feeding means. 

1. A dual dado machine for use with an elongated work member having top, bottom and end surfaces comprising an elongated main frame extending through two work sites, a magazine on said frame for supporting a stack of said work members, means on said main frame for transferring a work member from said stack in said magazine to said work sites simultaneously, means on said main frame for holding said work member in said work sites, a pair of dado cutters, means for simultaneously moving both of said dado cutters on said main frame transversely and each into and out of a respective one of said work sites, and means on said main frame for ejecting said work member from said main frame.
 2. A machine as in claim 1 including means responsive to the presence of a work member in said work sites for controlling operation of said transferring means.
 3. A machine as in claim 1 including means responsive to the presence of a work member in said work sites for controlling operation of said moving means.
 4. A machine as in claim 3 in which said controlling means is effective to move said dado cutters simultaneously into said work sites and then simultaneously out of said work sites.
 5. A machine as in claim 1 in which said moving means includes means for guiding said dado cutters to move in predetermined paths.
 6. A machine as in claim 5 in which said paths are converging.
 7. A machine as in claim 5 in which said paths are parallel.
 8. A machine as in claim 1 including means for urging said work member longitudinally in said work sites.
 9. A machine as in claim 8 including a datum block and in which said urging means is effective on an end of said work member in a direction toward said datum block.
 10. A dual dado machine for use with an elongated work member having top, bottom and end surfaces comprising an elongated main frame having a front portion and a rear portion, a pair of supports upstanding from said main frame in said rear portion thereof and spaced apart longitudinally of said main frame, dado cutter guides on said supports and extending transversely of said main frame, dado cutters movable along said guides, means on said main frame for simultaneously so moving said dado cutters, means on said main frame for holding a work member in a predetermined position for substantially simultaneous engagement by said moving dado cutters, and means for movably connecting at least one of said dado cutter guides to the respective one of said supports.
 11. A machine as in claim 10 including means for establishing a predetermined travel of said dado cutters on said guides.
 12. A machine as in claim 10 including means disposed on said front portion of said main frame for feeding a work member into said predetermined position on said main frame.
 13. A machine as in claim 10 including means on said main frame for ejecting a work member from said predetermined position into said front portion of said mainframe.
 14. A machine as in claim 13 including a conveyor on said main frame in said front portion thereof for receiving a work member from said ejecting means.
 15. A machine as in claim 12 including a magazine for a stack of work members mounted on said main frame in said front portion thereof and for supplying said work members to said feeding means. 